The extension of the natural-number domain to the integers in the transition from arithmetic to algebra

The work described in this article was based on a historical perspective in order to analyze the extension of the natural-number domain to the integers in students' transition from arithmetic to algebra in the context of word problems. The initial historical analysis showed the need to consider mutual interrelationships between the algebraic language and the methods of solving word problems and linear equations, for the understanding of the evolution of negative numbers. Four levels of acceptance of these numbers (subtrahend, relative number, isolated number and formal negative number) were extracted from the historical texts. The empirical analysis showed that the first three levels were observed among 35 students of 12–13 years old as well.This revised version was published online in September 2005 with corrections to the Cover Date.     

“What is a good digital library?” – A quality model for digital libraries

In this article, we elaborate on the meaning of quality in digital libraries (DLs) by proposing a model that is deeply grounded in a formal framework for digital libraries: 5S (Streams, Structures, Spaces, Scenarios, and Societies). For each major DL concept in the framework we formally define a number of dimensions of quality and propose a set of numerical indicators for those quality dimensions. In particular, we consider key concepts of a minimal DL: catalog, collection, digital object, metadata specification, repository, and services. Regarding quality dimensions, we consider: accessibility, accuracy, completeness, composability, conformance, consistency, effectiveness, efficiency, extensibility, pertinence, preservability, relevance, reliability, reusability, significance, similarity, and timeliness. Regarding measurement, we consider characteristics like: response time (with regard to efficiency), cost of migration (with respect to preservability), and number of service failures (to assess reliability). For some key DL concepts, the (quality dimension, numerical indicator) pairs are illustrated through their application to a number of “real-world” digital libraries. We also discuss connections between the proposed dimensions of DL quality and an expanded version of a workshop’s consensus view of the life cycle of information in digital libraries. Such connections can be used to determine when and where quality issues can be measured, assessed, and improved – as well as how possible quality problems can be prevented, detected, and eliminated.     

What will I be when I grow up? An analysis of childhood expectations and career outcomes

In this paper, we utilise the British National Child Development Study to explore the determinants of career expectations formed at the age of 16. We analyse the influence of careers advice and resources at school on career expectations as well as the influence of education. In addition, we explore the accuracy of occupational expectations as compared to the occupation that the respondents subsequently become employed in. Throughout our findings, human capital and gender play a pivotal role in explaining career expectations as well as explaining the accuracy of the occupational forecast. Interestingly, the level of school resources available for careers guidance in terms of the number of teachers who are qualified to give careers advice and the amount of specific careers guidance training received by these teachers both have relatively small effects upon career expectations.     

The impact of exercise training on the lipid peroxidation metabolomic profile and respiratory infection risk in older adults

Aging is associated with oxidative stress that may increase susceptibility to respiratory infections (RIs). We aimed to assess the impact of exercise training on the risk of RIs in older adults and on a targeted metabolomic profile of stress oxidative lipid peroxidation-related metabolites. Methods: In an 8-month clinical trial, 38 participants over 60 years of age were allocated to an exercise group (EG), in which participants underwent 90-min training sessions three times/week(n?=?20), or a control group (CG), in which participants maintained daily physical activities(n?=?18). Daily respiratory symptoms and RIs number and severity were collected. Serum by-products were assessed by comprehensive two-dimensional gas chromatography coupled to mass spectrometry with time of flight analyzer. Serum metabolomic profiling comprised 76 metabolites (alcohols, aldehydes, alkanes, and ketones). Principal components analysis and ANOVA-simultaneous component analysis were used to evaluate the metabolomic profile change. Results: The odds ratio of RIs for the EG was 2.0 CI 95% [0.2;25]. The incidence of RIs was 47% [23;70] in the EG vs. 44%[12;77] in the CG. The metabolomic profiling showed that alkanes and aldehydes classes differed between the EG and the CG before and after intervention. A calibration model showed a relation between the metabolites from four main classes (ketones, alcohols, alkanes and aldehydes) and the prediction of the number of RIs. Conclusion: Moderate exercise training, in older adults, compared with no exercise in controls, did not show a difference in the risk of RIs. A pattern of lipid peroxidation was associated with the number of RIs.     

The influence of content organization on student's cognitive structure in thermodynamics

Two different approaches to the content of thermodynamics were used in an introductory college physics course: one was the traditional organization found in most textbooks on the subject, the other was based on the learning theory of David Ausubel. The influence of these different content organizations on the student's cognitive structure was investigated using a word association test which was analysed through hierarchical clustering analysis. Research findings suggest that the approach based on Ausubel's theory influences the student's cognitive structure in such a way that their conceptual hierarchies are more coherent with the basic laws and the conceptual structure of the subject matter.     

Reflections of a Racial Queer

In this article, I reflect on my personal experiences of racial queerness. In an effort to speak my secrets, I explore my identity production as a Multiracial person by critically examining my positionality throughout various key stages in my life. I present Multiracial microaggressions –those accumulated moments that underscore my racial queerness and argue that these phenomena, while taxing, also confer agency. I propose a conceptual framework that incorporates both queer theory and borderlands theory as a potential framework from which to study how Multiracial individuals are positioned as racial queers. I argue that queerness, for the Multiracial individual, may denote both deviance (from the monoracial norm) and a unique individuality (stemming from one’s Multiracial background). By offering my testimonial as a racial queer and introducing the racial queer conceptual framework, I come a bit closer to naming my experience as a Multiracial individual and providing a space from which others can do the same.     

Designing and Developing Assessments of Complex Thinking in Mathematics for the Middle Grades

Designing an assessment system for complex thinking in mathematics involves decisions at every stage, from how to represent the target competencies to how to interpret evidence from student performances. Beyond learning to solve particular problems in a particular area, learning mathematics with understanding involves comprehending connections among mathematical ideas and applying them in ways that may not have been taught directly. A challenge in characterizing mathematical competency is to capture not only the variety of skills and concepts, but also their connections. Designing assessments based on learning progressions may be one way to respond to this challenge. We discuss our experience developing a learning progression and an associated task model for mathetical functions.     

Correlation Between Organizational Culture and Compensation Strategies Using Charles Handy's Typology

Alignment between management strategies, policies, and practices with organizational cultures holds great potential to meet the challenges of retaining professionals and maintaining their commitment. In this article, authors consider that when it is aligned with company strategy, compensation acts as an incentive for developing common visions within organizational culture.     

Analysis of the distance covered by Brazilian professional futsal players during official matches

The purpose of this study was to measure and characterise the distances covered by Brazilian professional futsal players. The trajectories of 93 players during five matches were obtained using an automatic tracking method. The distances covered were analysed for different game conditions: over the entire game and during the times when the ball was out of play and in play separately. When the entire game was considered, the results showed that there was a reduction in the total distance covered per minute from the first [median ± IQR (interquartile range): 97.9 ± 16.2 m/min] to the second half (median = 90.3 m/min; IQR = 12.0), and when only the in-play time was considered (first half: 136.6 ± 17.2 m/min; second half: 129.2 ± 16.7 m/min). The percentage of distance covered in the standing and walking velocity range was higher in the second half than in the first when considering the entire game (30.8% and 28.0%, respectively) and during the in-play time (19.3% and 16.2%, respectively). In conclusion, this study verified that futsal players reduced the physical performance during the second half.     

A Method to Increase Student Interaction Using Student Groups and Peer Review over the Internet

A method of peer review for student groups is proposed. In this method, groups of students publish their assignments results over the Internet. A fellow student group reviews their work and publishes their findings (on the Internet). Finally, the two groups debate their points of view in front of the class. The debate and healthy competition among groups give the students a chance to learn how to give and receive criticism in a constructive way. This should increase the students' ability to interact and work in groups, an important skill for computer science professionals.